1. Field of the Invention
This invention relates to an optical system for analyzing light from a sample holder. The optical system is particularly suitable for use in a single or multi-channel separation system. The present invention is also directed toward a method of optically analyzing light from a separation system using a spectrograph.
2. Background
Spectrographs are devices for separating electromagnetic radiation into its spectral components. Optical spectrographs can be used for analysis of samples, such as analyzing the chemical composition of nucleic acid samples in order to determine the nucleotide sequence of the sample. Currently, experiments in chemistry and biology typically involve evaluating large numbers of samples. Sequencing of nucleic acid samples is typically time consuming and labor intensive. Therefore, it is desirable that a large number of samples can be simultaneously analyzed. With large scale projects such as the Human Genome Project, it is desirable to increase throughput of nucleic acid sequencing.
Electrophoresis is an increasingly common method of performing analysis, e.g. sequencing, of biological substances in order to increase throughput. Electrophoresis is an electrochemical process in which molecules with a net charge migrate in a solution under the influence of an electric current. Electrophoresis using one or more capillaries which are illuminated by a laser has proven to be useful in analyzing biological substances. Existing systems are typically not well-adapted for imaging large numbers of samples with a small focal ratio and high light collecting ability. Therefore, there is a need for an apparatus and method that maintains a substantially uniform image quality over a large field of view. Preferably, such an apparatus is compact, simple, and reduces focusing problems.
The advantages and purposes of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages and purposes of the invention will be realized and attained by the elements and combinations particularly pointed out in the appended claims.
To attain the advantages and in accordance with the purposes of the invention, as embodied and broadly described herein, the invention includes an optical system for analyzing light from a plurality of samples. The optical system includes a plurality of sample holders, a collection lens, a reimaging lens, and a light dispersing element located between the collection lens and the reimaging lens. The collection lens is configured to receive and substantially collimate light from the samples. The light dispersing element is configured to spectrally disperse the substantially collimated light from the collection lens. The reimaging lens is configured to receive light from the light dispersing element and direct the light onto a light detection device.
In another aspect of the present invention, the invention is directed towards a system for analyzing light from a sample in a separation system. The system includes at least one separation lane, a collection lens, a reimaging lens, and a light dispersing element located between the collection lens and the reimaging lens. The light source provides an excitation light to the at least one separation lane. The collection lens is configured to receive and substantially collimate light emitted from the separation lane. The light dispersing element is configured to spectrally disperse substantially collimated light from the collection lens. The reimaging lens is configured to receive dispersed light from the light dispersing element and direct the light onto a light detection device. In certain embodiments, the system may include a light source providing an excitation light to the at least one separation lane. In certain embodiments, the system may include a plurality of the separation lanes.
In yet another aspect of the present invention, the invention includes an optical spectrograph for analyzing light from at least one sample. The optical spectrograph includes at least one source of excitation light for illuminating at least one sample holder, a first lens unit, a transmission grating, a second lens unit, and a light detection device having a plurality of detector elements. The first lens unit has at least one lens and is configured to receive and substantially collimate light from the sample holder. The excitation light from the source of illumination does not pass through the first lens unit prior to illuminating the at least one sample holder. The transmission grating is configured to spectrally disperse substantially collimated light from the first lens unit. The second lens unit has at least one lens and is configured to receive light from the transmission grating and direct the light onto the light detection device.
In a further aspect of the present invention, the invention is directed toward a method of optically analyzing at least one sample. The method includes providing at least one holder having a sample therein, illuminating the sample with an excitation light to generate an emission light, and collecting the emission light from the sample with a collection lens. In certain embodiments of the method, the excitation light does not pass through the collection lens prior to illuminating the sample. The emission light is substantially collimated by the collection lens. The method further includes spectrally dispersing the substantially collimated emission light beam with a transmission grating, directing the emission light from the transmission grating onto a light detection device by a reimaging lens, and optically detecting the spectral characteristics of the emission light. In certain embodiments, a plurality of sample holders are provided.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.